1. Field of the Invention
The present invention relates to a zinc oxide type arrester and, in particular, relates to a zinc oxide type arrester having a plurality of constitutional units each of which is composed of a plurality of columnar stack bodies.
2. Description of Related Art
A conventional zinc oxide type arrester having the above structure is disclosed in JP-A-56-164502(1981) which is illustrated in FIG. 8. In the conventional zinc oxide type arrester, four constitutional units 100, 200, 300 and 400 are disposed within a closed container 50 in which SF6 gas is filled and each of the constitutional units is constituted by four columnar stack bodies a, b, c and d, and each of which is formed by stacking zinc oxide elements and insulating spacers. The respective columnar stack bodies a, b, c and d in the respective constitutional units are positioned at respective apexes of imaginary quadrangles and are electrically connected via bridge conductors 4 in such a manner that the columnar stack bodies a, b, c and d are wound in an order of a, b, c and d. The order of winding is identical in the respective constitutional units 100, 200, 300 and 400, however the respective constitutional units are arranged by rotating their respective columnar stack bodies a, b, c and d in their juxtaposed direction so that the columnar stack body b in the constitutional unit 100 adjoins with the columnar stack body b in the constitutional unit 200, the columnar stack body a in the constitutional unit 200 with the columnar stack body a in the constitutional unit 300, the columnar stack body d in the constitutional unit 300 with the columnar stack body d in the constitutional unit 400 and the columnar stack body c in the constitutional unit 400 with the columnar stack body c in the constitutional unit 100.
In the above arrangement of the respective constitutional units, the columnar stack bodies having the same stacking structure of the zinc oxide elements and the insulating spacers are arranged so as to face each other, such that the potentials along the stacking direction, namely the height direction, of the facing columnar stack bodies in the neighboring constitutional units are substantially the same, therefore the facing columnar stack bodies can be arranged closely each other to thereby reduce their insulating distance.
However, in the conventional zinc oxide type arrester explained above, the constitutional units 100, 200, 300 and 400 having an identical structure are employed and are disposed in the closed container 50 while merely rotating the same in the juxtaposed direction of their columnar stack bodies a, b, c and d depending upon their locations in the manner as explained above, therefore, the diameter of the closed container 50 which accommodates the entire constitutional units is caused to be increased. Namely, totally eight columnar stack bodies facing to a center of the closed container 50, the columnar stack bodies c and b for the constitutional unit 100, b and a for the constitutional unit 200, a and d for the constitutional unit 300, and d and c for the constitutional unit 400 are disposed on a substantially same imaginary circle, therefore the large space at the center of the closed container 50 is remained unused which causes to increase the diameter of the closed container 50 accordingly.